wc: Count Things

How many lines in this file? How many words? wc tells you:

wc file.txt

Output: 42 156 1089 file.txt

That's 42 lines, 156 words, 1089 bytes. Simple stats.

Getting Specific

Usually you just want one number:

Lines only:

wc -l file.txt

Words only:

wc -w file.txt

Bytes/characters only:

wc -c file.txt

The -l Flag Lives at the End of Pipelines

This is wc's most common use - counting how many results came through:

How many errors?

grep "error" log.txt | wc -l

How many files match?

find . -name ".txt" | wc -l

How many unique entries?

sort data.txt | uniq | wc -l

Multiple Files

wc .txt

Shows stats for each file, plus a total.

Quick Reference

| What you want | Command | |---------------|---------| | All stats | wc file | | Line count | wc -l file | | Word count | wc -w file | | Byte count | wc -c file | | Count pipe results | command \| wc -l |

Practice

In CTF challenges, wc -l is your sanity check. "Did my grep find anything?" "How many files am I dealing with?"

wc is the simplest possible question: how many?